The present invention pertains to cellular communication systems and more particularly to a method for increasing the probability of signaling or control messages being successfully transmitted over the air in a cellular communication system.
For establishing voice communication between cellular users, control or signaling channels are required as well as a traffic channel. The traffic channel carries, among other things, voice samples of each person speaking. While the signaling or control channels contain system control information, for example, such as hand off related messaging for a moving cellular subscriber from one cell to another.
In current cellular communication systems, over the air controller signaling messaging is frequently performed “in-band”. That is, when a call controller signaling message is required, bits or entire frames are “stolen” from the traffic channel which is used to carry the voice or data in order to carry the necessary signaling or control information. For example, in a cellular communication system, hand off direction messages, power control parameter messages, neighbor list updates, etc. may be sent to a mobile unit “in-band” on a traffic channel. If this “in-band” messaging occurs too frequently, it can negatively impact the voice quality of the traffic channel since bits are being omitted from a speech stream in order to carry signaling or control messages.
This may contrast with the fact that call control signaling information must be reliably transmitted in a fast manner in order to achieve good call performance, that is, a low dropped call rate and low noise RF traffic channels. One method to increase such call performance is to quickly or rapidly repeat certain call critical messages. Quick repeating is a process of sending the same message multiple times in rapid succession in order to increase the likelihood that a particular message will be received reliably by the mobile unit.
Existing communications that address this problem at all provide a static mechanism for quickly repeating call critical control messages. These methods do not take into account voice quality impacts or data throughput. Existing methodology may quickly repeat critical messages in a static fashion, but this typically has a negative impact on voice quality.
Accordingly, it would be highly desirable to have an adaptive method for in-band signaling for providing improved call reliability by the reception of call critical control or signaling messages while avoiding an impact upon voice quality of the traffic channel.